Method of treating wood



Patented Jan. 3, 1939 UNITED 1 STATES PATENT? OFFICE.

amass METHOD OF TREATING. WOOD Thomas ltobimon, Smithtown, N. 1., assignor to Lancaster Processes Inc., New York, N. Y., a corporation of York No Drawing. Application December 18, 193

' Serial 3 Claims. (otsz-o) for various purposes, such as in the production of a plastic composition suitable for conversion :cto various articles, such as roofing elements, In carrying out the new method, the wood ll used, for example. pine, consists of stumps,

branches, and otherwise unusable or waste pieces, and this wood is first reduced to chips or splinters of relatively small size, as for instance not sub-- stantially exceeding two inches in, longest diieo mension. These'chips are first reduced to the form of individual fibres or loosely associated fibre bundles, and I have found that this operation can be carried on rapidly and at low cost in a mixer of the internal type in which there are rotating elements cooperating with one another and with the inner walls of the mixing chamber to act on the pieces of .wood with a rolling,

crushing, and rubbing action. The pieces of wood are introduced intothe mixer preferably with a small quantity of water, and are subjected to the defibering operations in the mixing chamber while under pressure.

. In theoperation of the mixer, the wood is defibered and the water present in the mixture facilitates this action by softening the wood and the substances which bind the fibres together. For

best results, the operation is continued until the wood is reduced to the form of small fibre bundles loosely bound together and individual fibres, since the extraction may be carried on more easily and with a greater recovery from the wood in that condition, and the wood remaining is in a condition suitable for various uses, suchas the production of the plastic compodtion.

Y The internal mixer which I prefer to employ for the purpose is that commonly used in the rubber industry and known commercially as the Banbury mixer. This mixenas now constructed and as illustrated in one form in Patent No. '50 1,523,387, includes operating elements which rotate within the mixing-chamber and subjectthe wood under treatment to rubbing and crushing against the walls of the chamber. In addition, the mass of wood is maintained under pressure,

, stab that'as the elements rotate, they cause the pieces of wood to rub against one another, the elements acting on the mass with a churning action. In this operation, the wood is reduced to the form of individual fibres and small fibre bundles, and the fibres and fibre bundles are I twisted and bent so that the rosin ducts therein are disrupted and broken down.

After the reduction of the wood has been continued to the desired point, the fibrous material is discharged and is now ready for distillation by in means of steam. In the reducing operation, the

- rosin ducts in the wood have been broken down and the extraction of the rosin is therefore 'greatly facilitated. The distillation may be carried on in any suitable type of apparatus as, for example, a vessel having a false bottom on which the ma- .terial is placed, the steam being injected from below and passing up through the fibrous mass so as to carry oil with it the more volatile compounds present in the wood. In the distillation 20 operation, the rosin exudes from the ducts and remains on the surfaces of the fibres so that the fibres are substantially encrusted with therosin, whereas when the wood has been reduced only tochi-p form, a large part of the rosin remains in 25 I the ducts so that its removal is relatively diiiicult. The wood is subjected. to steam distillation for a sufllcient length of time to remove all or =substantially all of the turpentine, pine oils, and other volatile materials; and when that operation 30 has been completed, the wood is dried as a preliminary to the removal of the rosin. This drying operation can be carried on in .any suitable drying equipment, and if desired, the wood may remain in the extracting vessel, hot air being in- 35 troduced to eifect the desired drying. After the drying has been carried "on to an extent such that only a relatively small amount of moisture remains in the woody mass, the rosin is extracted. by

means of a suitable solvent, such as naphtha. o

This operation may be carried on in any suitable extracting apparatus and is preferably performed by causing the solvent to flow through the woody mass a number of times so as to insure thorough removal of the rosin. By reason of the 5 reduced form of the wood and the presence of the rosin on the surfaces of the fibres, the removal of the rosin is easy and a largeproportion of'the rosin can be recovered in a short time.

When the extraction of the rosin by means of so the solvent has been completed, the woody material is subjected to steam distillation for a' short time to drive oil any solvent which remains be hind. This treatment with steam not only p'ermits the recovery-of the solvent still adhering to soft, wet, and substantially free fromresins and other gummy substances; vHeretofore, the woody material remaining after the extraction of the turpentine and rosins has been discarded .as useless orfit only for. fuel, but I have found that the soft wet material is admirably adaptedfor usein the production of a plastic composition and it'may beused at once and without further treatment in the production of that co'mposition.

, The method 'of producing the plastic composition which I'prefer to employ is that disclosed in my copending application Serial-No. 54,714, filed.

December 16,1935. According to that method,

the soft fibrous material is treated in an internal l mixer, such as the Banburymixer above referred to, in the presence of asuitable binder, such as there should be a 'sufilcient amount of waterasphalt, the binder being introduced gradually as the operation proceeds; For best results inthe production of the plastic, I findit isdesirable that present'in the mixer to insure the formation of an inverted emulsion of asphalt, that is, one in which the water is dispersed through the asphalt. ,The-

woody material may, as a result oithe final steam. distillation, contain enough moisture for that purpose. but if the distillation has not beencontinned to a sufiicient extent to insure the presence of the required amount of moisture, the deficiency may be made up by introducing water intothe mixer with the wood and asphalt.

- fibr'illae present thereon, and the presence ofmixer, the fibres'in the discharged mass have In this final operation in the mixer, the fibrous mass is thoroughly dispersed through the binder so that the latter. coats and to some extent impregnates the'individual fibres. The fibrous material is subjected, in the mi xer, not only to themechanical action of-the'rotating members, but also to hydraulic shear applied by the members through the viscous'binding material. As a re.-

sult of these actions, the fibre bundles are broken down and the fibres remain in single fibre form.

These fibres arecharacterized by their extra= ordinarylength and the unusual number of the fibrillae in such amount is the result of the shearing action applied through the emulsified binding medium. Upon discharge from the the characteristicsreferred -to. The plastic mass taken from the mixer maybe extruded, pressed, and otherwise formed into various ar- -.ticles which are characterized by great. rigidity and strength, high electrical and thermal insulating power, low susceptibility to heat changes, and capability 'of beingcut, sawn,-and nailed without fracture.

- The new method oifers'many advantages. over that heretofore employed in the recovery of tur-, pentine and similar substances from wood in'that thepreliminary reduction of the wood in the internal-mixer reduces the wood to a condition such that the recovery-of the volatiles and resin- $1,142,839 the fibres, but also leaves the fibrous material ous substances may'be carriedjon' rapidly and with a greater recovery than has been possible when the wood is in the'form of chips. or splinters. Also, after the extraction operation, the wood is inan ideal condition for the production of the plastic, since it has been-reduced almost tothe desired finalzform and is softand moist. The new method therefore not only insures a greater output of the extracted substances from a given quantity of wood in a shorter time, but also makes. available a supply of fibrous material which can be used at once in the production 01' a valuable plastic composition, instead of having to be discarded as waste or used only as fuel. I

I claim:

defibering wood by subjecting amass of small pieces of natural wood, while under pressure and in the presence-of not more than a relatively small amount-of water, to mechanical action which will cause the individual pieces of the wood of the mass to bejrubbed one against an- ,other until said pieces are broken down into a state of elementary fibres and small fibre bundle" in which the rosin ducts have been disrupted and the rosin therein is exposed on the surface of the fibres, and treating the fibrous material 15 .-l. A method of treating wood-which comprises so produced with a solvent toextract the resins .and similar substances therefrom.

A method of treating wood which comprises defibering wood by subjecting a mass of small pieces of natural wood, while under pressure and in the presence of not more than a relatively small amount, of water, to mechanical action -which will cause the individual pieces of the wood of the mass to'be rubbed one against another until said pieces are broken down into a statelof elementary fibres and small fibre bundles in which the rosin ducts have been disrupted and- I the'rosin therein. is exposed on the surface of the fibres, and recovering volatile substances and resin and similar substances from the fibrous maof the mass to be rubbed one against another until said pieces are broken down into a state of elementary fibres and small fibre bundles in which the rosin ducts have been disrupted and the rosin therein is exposed .on the surface of the fibres, recovering volatile substances from the fibrous material so produced by means'oi steam, extracting resins and similar substances from-the fibrous material bymeans or a solvent, and removing the solvent from the residual fibrous material by steam.

- THOMAS ROBINSON. 

